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$xhtml = array(
	'<{title}>' => 'Backups',
	'<{subtitle}>' => 'Written in <span title="Databases 2">CS 3306</span> by <a href="https://y.st./">Alexand(er|ra) Yst</a>, finalised and <a href="https://y.st./en/coursework/CS3306/Backups.xhtml">archived</a> on 2019-05-15',
	'<{copyright year}>' => '2019',
	'takedown' => '2017-11-01',
	'<{body}>' => <<<END
<div class="APA_title_page">
	<p>
		Backups<br/>
		Alexand(er|ra) Yst<br/>
		<span title="Databases 2">CS 3306</span>
	</p>
</div>
<h2>On terminology</h2>
<p>
	In our reading assignment this week (Stanek, n.d.), we looked at different types of backups that can be performed on Windows-based machines.
	In particular, we looked at full backups, differential backups, and incremental backups.
	While these types of backups can be obviously be performed on non-Windows machines as well, the search terms &quot;differential backup&quot; and &quot;incremental backup&quot; seem to only pull up Windows-related results.
	My best guess is that these terms are Windows-specific, and if you want to implement the same backup strategies on a non-Windows system, other terminology is typically used.
</p>
<h2>Full backups</h2>
<p>
	To understand differential and incremental backups, it&apos;s helpful to start with the groundwork of understanding full backups.
	In a full backup, everything within the target area is backed up (Acronis, n.d.).
	For example, you could perform a full backup of a drive, and everything on that drive would be backed up.
	You could perform a full backup of a directory, and everything in that directory and recursively throughout all its subdirectories would be backed up.
	This type of backup is very reliable, as it can alone be used to restore all the data it backed up when needed.
	However, it&apos;s also the slowest type of backup to perform and takes the most space, as literally everything gets backed up.
</p>
<h2>Differential backups</h2>
<p>
	Differential backups back up only data that has been changed since the last full backup (Acronis, n.d.).
	Due to the way differential backups and incremental backups are implemented in Windows, if you mix differential and incremental backups, a differential backup will actually back up only files that have been added or that have changed since the last full backup <strong>*or*</strong> incremental backup, whichever came later (Stanek, n.d.).
	Either way, a differential backup only saves the files that have changed (or been created) since the last non-differential backup.
	This takes up less space and less time than a full backup.
	It&apos;s more prone to data loss than a full backup, as you need to have the differential backup, the full backup, and any incremental backups made in between in order for the backup restoration to be successful, but if you&apos;re only using full backups and differential backups, is very reliable.
	You need only the latest differential backup and the latest full backup in order to restore your data to the last backed-up state.
</p>
<h2>Incremental backups</h2>
<p>
	Incremental backups are the fastest to perform and take the least amount of space.
	They save only what has been added or has changed since the previous full or incremental backup, whichever came later (Acronis, n.d.).
	However, these backups are also the least reliable (Acronis, 2016).
	In order to restore from an incremental backup, you must have intact the latest full backup as well as <strong>*every*</strong> incremental backup since then.
	If <strong>*any*</strong> of these backups are corrupted or lost, the restoration will fail.
	Restoring from incremental backups is also slow, as the restored files need to be copied from several incremental backups instead of a single full backup.
</p>
<h2>Conclusion</h2>
<p>
	Full backups really are the most reliable.
	However, they also take the most time to perform.
	It&apos;s a trade-off, and while performing full backups periodically should definitely be done, the frequency at which you perform them depends on your needs.
	Incremental backups are the fastest to perform, but are also the most prone to data loss.
	Each incremental backup performed is a single point of failure, and if any of those backups are lost, any incremental backups taken after those backups are effectively lost as well.
	Differential backups rely on the previous full backup, but not previous differential backups.
	In my opinion, they&apos;re a great middle ground between making full backups every time and making incremental backups most of the time.
	Using the tape rotations we discussed this week, making one full backup each week and making an incremental backup each other day seems like a good level of reliability without making too much of a time investment.
</p>
<div class="APA_references">
	<h2>References:</h2>
	<p>
		Acronis International GmbH. (2016, March 28). <a href="https://www.acronis.com/en-us/blog/posts/tips-tricks-better-business-backup-and-recovery-world-backup-day">Tips &amp; Tricks for Better Business Backup and Recovery for World Backup Day</a>. Retrieved from <code>https://www.acronis.com/en-us/blog/posts/tips-tricks-better-business-backup-and-recovery-world-backup-day</code>
	</p>
	<p>
		Acronis International GmbH. (n.d.). <a href="https://www.acronis.com/en-us/articles/incremental-differential-backups/">What&apos;s the difference between differential and incremental backups (and why should I care)?</a>. Retrieved from <code>https://www.acronis.com/en-us/articles/incremental-differential-backups/</code>
	</p>
	<p>
		Stanek, W. R. (n.d.). <a href="https://my.uopeople.edu/pluginfile.php/476020/mod_book/chapter/187042/MSDataBackupRec.pdf">Chapter 14: Data Backup and Recovery from Microsoft Windows 2000 Administrator&apos;s Pocket Consultant</a>. Retrieved from <code>https://my.uopeople.edu/pluginfile.php/476020/mod_book/chapter/187042/MSDataBackupRec.pdf</code>
	</p>
</div>
END
);
